We are British. My 17yo recently travelled abroad to an EU country for a holiday with another family (who live in the UK but are originally from the country they were travelling to). I sent her with a permission letter and provided my and DH's contact details and passport details and a copy of her birth certificate. She wasn't asked for any of this either in the UK or the other country, or any information about who she was travelling with or why. AIBU to be surprised by this? Obviously my daughter was completely safe but is this not a concern for trafficking or other reasons?